A quick tour at the Rubin (Indian Meadow) Conservation Land in Boxborough

I was here long ago but missed the things seen by reader b. downing.  Egged on by his report, I went for another look and, as he said: some large messy indistinct platforms at the end of the red trail. This was the edge of an orchard, 

Were these just from field clearing? Here is a first one, rectangular and messy, part way out the spit of land:

This ones had a couple of possible niches:

 Or is this a "hollow"?

Onward.

There was a second one at the north end of the higher ground before the swamp:

 

It had a bit of structure:

In the end these might be my old friends: rectangles with hollows, but they could have been dumped from the orchard. Still not sure. So I headed north, clockwise around the swamp. 

Here is a beautiful split-wedged rock:

I saw a few other odds and ends: a rock-on-rock, a gateway pile. But the best reward came 3/4 of the way around, just behind 343 Sargent Rd. This one is more clearly rectangular and more clearly undisturbed:

Note the lower portion to the left - which I think is equivalent to the"tail" that appears on some other piles.